title: Replacement of cetyltrimethylammoniumbromide bilayer on gold nanorod by alkanethiol crosslinker for enhanced plasmon resonance sensitivity.
abstract: Surface modification of gold nanorods (GNRs) is often problematic due to tightly packed cetyltrimethylammoniumbromide (CTAB) bilayer. Herein, we performed a double phase transfer ligand exchange to achieve displacement of CTAB on nanorods. During the removal, 11-mercaptoundecanoic acid (MUDA) crosslinker is simultaneously assembled on nanorod surfaces to prevent aggregation. The resulting MUDA-GNRs retain the shape and position of plasmon peaks similar to CTAB-capped GNRs. The introduction of carboxyl groups allows covalent conjugation of biological receptors in a facile fashion to construct a robust, label-free biosensor based on localized surface plasmon resonance (LSPR) transduction of biomolecular interaction. More importantly, smaller MUDA layer on the GNRs reduces the distance of target binding to the plasmonic nanostructure interface, leading to a significant enhancement in LSPR assay sensitivity and specificity. Compared to modification using conventional electropolymer adsorption, MUDA-coated gold nanosensor exhibits five times lower detection limit for cardiac troponin I assay with a high selectivity.
authors.affiliation: Department of Biomedical Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Casas
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Venkataramasubramani
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Tang
mesh_terms: D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties
chemical_list: D002593:Cetrimonium Compounds; D003432:Cross-Linking Reagents; D013438:Sulfhydryl Compounds; D006046:Gold; D000077286:Cetrimonium
keywords: Biosensing; Functionalization; Gold nanorod; Surface modification; Surface plasmon resonance